As a new type of fishery cultivation equipment, the deep - sea aquaculture cage can cultivate fish with high economic value in the sea areas far away from the land. In order to explore the possible damage that the instability of the net - hanging poles may cause to the main structure of the platform, this paper takes a certain aquaculture platform in Guangdong as an example. Using finite - element software, displacements in different directions sufficient to cause fracture in the poles are applied to the free ends of the net - hanging poles. These displacements are designed to study the cracking process and ultimate bearing capacity of the typical nodes when they are subjected to forces in different directions. Different - thickness outer plates of the floating boxes are also set up to study the influence of the relative stiffness between the outer plates and the net - hanging poles on the fracture behavior and ultimate bearing capacity of the typical nodes. Through numerical calculations, it is found that when the same load is applied to the typical nodes with different plate thicknesses, the main structures of the 6 - mm and 8 - mm outer plates crack first, while for the 10 mm and 12 mm outer plates, the net - hanging poles fracture before the main structures. The results show that when the relative stiffness increases from 0.5 to 0.67, the weight increases by 8.8%, and the deformation - resistance capacity increases by 44%; when the relative stiffness increases from 0.67 to 0.83, the weight increases by 8.1%, and the deformation - resistance capacity increases by 33%; when the relative stiffness increases from 0.67 to 1, the weight increases by 7.5%, and the deformation - resistance capacity increases by 25%. It can be considered that the increase in the steel material of the typical nodes has little effect on the improvement of the ultimate bearing capacity, and an appropriate reduction in the plate thickness can be considered in the platform design stage. The analysis results show that if the stiffness of the main structure of the aquaculture cage is much greater than that of the poles, the fracture phenomenon is usually limited to the welds and the roots of the net - hanging poles and cannot extend to the main body of the aquaculture cage, resulting in only local plastic deformation of the main structure. On the contrary, when the stiffness of the main body of the aquaculture cage is lower than or close to that of the poles, the main structure of the node fractures first, and the fracture area gradually expands to the pole part. The results also show that the ultimate bearing capacity of the typical nodes of the net - hanging poles increases significantly with the increase in the thickness of the outer plates of the floating boxes. Based on this discovery, this paper proposes the calculation equations for the ultimate bearing capacity of the typical nodes in various directions, providing a theoretical basis for relevant engineering designs.